Apparatus for mounting semiconductor devices

ABSTRACT

Semiconductor devices are mounted on corresponding lead frames by being inserted into apertures of a masking member in a desired registration with the lead frame strip.

This invention is a continuation-in-part of copending application Ser.No. 307,374, filed Nov. 17, 1972, for Improvements Related to LeadFrames, The Manufacture Thereof and The Mounting of SemiconductorDevices Thereon, a divisional thereof; Ser. No. 457,545, being filedApr. 3, 1974.

This invention relates to the mounting of semiconductor devices onsupports, each support including a matrix of conductors initially in theform of a lead frame, the lead frame being part of a load frame strip, aplurality of identical lead frames being uniformly distributed along,and being uniformly oriented with respect to, the longitudinal axis ofthe strip. The lead frames may be formed in a metal layer on a compositebody comprising the metal layer on a major face of an insulatingsubstrate.

Each lead frame of the strip may comprise the support for asemiconductor device; or may comprise a carrier lead frame which isbonded, for example, to a larger, main lead frame, or to a conventionalheader arrangement, to complete the support for the semiconductordevice. The semiconductor device on its support is then encapsulated bybeing moulded within a plastics material or by being enclosed in ahermetically-sealed, evacuated enclosure. At least a part of theconductor matrix of the lead frame is encapsulated with thesemiconductor device, the conductor matrix being wholly encapsulated ifit initially comprised part of merely a carrier lead frame of thesupport for the semiconductor device.

The conductor end portions of the conductors of each lead frame of sucha strip is arranged to be such that a corresponding semiconductordevice, when correctly oriented, is capable of being mountedsatisfactorily on the lead frame by each device contact being connectedexclusively to a co-operating conductor end portion.

Previously it has been known to use precision optical aligning means toensure that the corresponding semiconductor devices are sufficientlyaccurately located on the end portions of the conductors of the leadframes of such a strip, in order to arrange that each device contact maybe connected exclusively to a co-operating conductor end portion.

It is an object of the present invention to provide novel apparatus formounting corresponding semiconductor devices onto such a lead framestrip, which apparatus ensures that, without employing precision opticalaligning means, the devices are sufficiently accurately located on theco-operating end portions of the conductors of the lead frames for thesubsequent satisfactory mounting of the devices.

According to the present invention apparatus for mounting semiconductordevices each rectangular-shaped in plan on a strip of corresponding leadframes, the lead frames being uniformly spaced along the longitudinalaxis of the strip, each lead frame having a matrix of conductors,comprises a masking member defining at least one rectangular-shapedaperture, means for feeding the lead frame strip longitudinally throughpart of the apparatus with the aperture defined in the masking memberbeing in a desired registration on a lead frame of the lead frame strip,conductor end portions for connection to contacts of a correspondingsemiconductor device being exposed through the aperture, the arrangementof the lead frame and the aperture being such that when a correspondingsemiconductor device is inserted in the required orientation into theaperture each device contact is exclusively opposite to a co-operatingconductor end portion, and in said part of the apparatus there isincluded means to bond the device contacts to the co-operating conductorend portions.

In one form of the apparatus the aperture defined in the mashing membermay have dimensions to allow a corresponding semiconductor device to bea sufficiently close fit within the aperture, to ensure that each devicecontact exclusively is opposite to the conductor end portion to whichthe contact is to be connected, when the masking member is in therequired registration with the lead frame.

In another form of the apparatus the arrangement of the lead frame stripand the aperture defined in the masking member may be such that thefollowing walls of the aperture as the masking member is fed through theapparatus are inclined in relation to the longitudinal axis of the leadframe strip, and each device contact exclusively is opposite to theconductor end portion to which the contact is to be connected when themasking member is in the required registration with the lead frame andthe device is contiguous with the following walls of the aperture. Meansmay be provided to ensure that the corresponding semiconductor device iscontiguous with the following walls of the aperture when the maskingmember is in the desired registration with the lead frame.

The aperture defined in the masking member may be square-shaped in plan,being arranged to receive a corresponding semi-conductor device which isalso square-shaped in plan.

The masking member may define a plurality of apertures, the arrangementbeing such that consecutive apertures expose conductor end portions ofconsecutive lead frames of the lead frame strip.

Automatic means for inserting correspoding semiconductor devices in eachaperture defined in the masking member when the masking member is in thedesired registration with the lead frame strip may be provided; or thedevices may be inserted manually.

According to another aspect of the present invention a method ofmounting semiconductor devices each rectangular-shaped in plan on astrip of corresponding lead frames, the lead frames being uniformlyspaced along the longitudinal axis of the strip, each lead frame havinga matrix of conductors, comprises placing in the desired registration ona lead frame of the lead frame strip a masking member defining at leastone rectangular-shaped aperture, conductor end portions for connectionto contacts of a corresponding semiconductor device being exposedthrough the aperture, inserting a corresponding semiconductor device inthe required orientation into the aperture so that each device contactis exclusively opposite to a co-operating conductor end portion, andbonding the device contacts to the co-operating conductor end portions.

The present invention will now be described by way of example withreference to the accompanying drawings, in which

FIG. 1 is a plan view of part of a carrier lead frame strip,

FIG. 2 is an elevation of one embodiment of apparatus according to thepresent invention for mounting semiconductor devices on the carrier leadframes of the strip of FIG. 1, the apparatus employing a meshing memberthrough apertures defined in which, whilst the mounting operation isbeing performed, the co-operating end portions of the conductors of thecarrier lead frames to be connected to the corresponding semiconductordevices are exposed,

FIG. 3 is a plan view of the masking member when on the carrier leadframe strip,

FIG. 4 is a section through part of a carrier lead frame of the strip,and also shows a corresponding semiconductor device ready to be mountedon the carrier lead frame,

FIG. 5 is a plan view of a carrier lead frame, carrying a semiconductordevice, and secured to a larger main lead frame to complete the supportfor the semiconductor device,

FIG. 6 shows a completed package for the semiconductor device, thepackage being in the form of a so-called "flat pack", in which packagethe device and the carrier lead frame of FIG. 5 are encapsulated in anepoxy resin,

FIG. 7 is a plan view of another embodiment of a lead frame strip,

FIG. 8 is a plan view of the masking strip when on the lead frame stripof FIG. 7, and

FIG. 9 is a section on the line IX -- IX of FIG. 8, and also shows acorresponding semiconductor device ready to be mounted on the lead framestrip.

FIG. 1 shows part of a strip 10 comprising a plurality of identicalcarrier lead frames 11. The carrier lead frames 11 are for use insupports for corresponding semiconductor devices, and are uniformlydistributed along, and are uniformly orientated with respect to, thelongitudinal axis of the strip 10, the longitudinal axis being indicatedby the broken line 12. The carrier lead frames 11 are supported on aflat, elongated, insulating substrate 13 of uniform width, and are shownbetween the constituent conductors 14 of the carrier lead frames 11. Theinsulating substrate 13 is of a polyimide and is sufficiently thick toprovide the requisite support for the carrier lead frames 11.

Initially sprocket holes 15 are precisely punched adjacent to thelongitudinal edges of the substrate 13, to ensure that the substrate isaccurately positioned both in apparatus for forming the carrier leadframes 11, and in apparaturs for mounting corresponding semiconductordevices on the carrier lead frames 11.

The carrier lead frames 11 are formed in a layer of silver evaporativelydeposited on the substrate 13, the thickness of the silver layer havingthe desired thickness for the carrier lead frames. The carrier leadframes 11 are then formed from the silver layer in a precise manner, bya known method employing photolithographic etching techniques. Thus, thecarrier lead frames 11 are precisely located on the substrate 13 and, inparticular, inner end portions 16 of the conductors 14 of the carrierlead frames are precisely located in relation to the sprocket holes 15.

The parts of the silver layer extending between the carrier lead frames11 are not removed and hence, each carrier lead frame is part of anintegral structure formed within the silver layer. The carrier leadframes are completed by electrolytically depositing on their exposedsurfaces a layer of tin 17, shown in FIG. 4.

Each semiconductor device when satisfactorily mounted on a lead frame ofthe strip 10 has a contact connected to a conductor 14 of the leadframe. Thus, the pattern of the inner conductor end portions 16 of eachcarrier lead frame 11 corresponds to the pattern of contacts on eachdevice.

The apparatus 20 by which the semiconductor devices 21 are mounted onthe lead frames is shown partially, and in diagrammatic form, in FIG. 2.The strip 10 of carrier lead frames is fed in a controlled manner over aworktable 22 by engagement of the sprocket holes 15 with two sprocketwheels 23, a wheel 23 being at either end of the worktable 22, thewheels 23 being rotated by control means (not shown). The strip 10 isfed between reels 24, the reels being changed when the strip 10 haspassed over the worktable 22. An elongated masking member 25 of thepolyimide is passed over the lead frame strip 10 whilst it is on theworktable 22. Movement of the strip 10 and member 25 is from right toleft as viewed in the drawing and is represented by the arrow identifiedby reference character 9. The masking member 25 is of the same width asthe lead frame strip 10 and is provided with sprocket holes 26 (notshown in FIG. 3), accurately punched along its longitudinal edges in thesame manner as the sprocket holes 15 of the lead frame strip 10. Thesprocket holes 26 in the masking member 25 are such that the maskingmember may be passed over the worktable 22 on the lead frame strip 10with the sprocket holes 26 being engaged by the sprocket wheels 23.Hence, the sprocket holes 26 of the masking member are required to beslightly different size, and to be spaced apart by a slightly differentamount, than the sprocket holes 15 of the strip 10, in order to takeinto account the curvatuve of the sprocket wheels 23.

Thus, the masking member 25 is precisely located on the lead frame strip10 and is fed in the same controlled way as the lead frame strip overthe worktable 22, between reels 27, via idlers 28, and via the sprocketwheels 23. The reels 27 are changed over when the masking member 25 haspassed over the worktable 22.

The masking member 25 is pre-formed by precisely punching identicalsquare-shaped apertures 30 uniformly distributed along the longitudinalaxis of the member 25, as shown in FIG. 3, and simultaneously with thepunching of the sprocket holes 26. The apertures 30 are arranged to bein such a relationship to the sprocket holes 26 that, with the maskingmember 25 in the desired registration with the carrier lead frame strip10 on the worktable 22, the inner end portion 16 of each conductor 14 ofthe strip 10 is exposed. FIG. 3 is a plan view of the masking member 25whilst on the worktable 22 of the apparatus 20, and the carrier leadframes 11 beneath the masking member 25 are indicated in broken lineform, except for the conductor end portions 16 exposed through theapertures 30.

As shown in FIG. 4, the length of each side of each square-shapedaperture 30 in the masking member 25 is such that the square-shapedsemiconductor devices 21 to be mounted on the carrier lead frames 11 area close fit within the aperture 30. This Figure comprises a section ofthe masking member 25 on the carrier lead frame strip 10, and shows acorresponding semiconductor device ready to be mounted on a carrier leadframe. Sufficiently accurate registration between the contacts on thedevices 21 and the co-operating conductor end portions is ensured byarranging that the devices are a close fit within the aperture 30.

Each semiconductor device 21 is formed in a known manner, and hascontacts 32 comprising hemispherical solder protrusions on a passivatedsurface 33 of the device. The protrusions are formed on selected partsof aluminum conductors on the passivated surface 33, the selectedaluminum parts being rendered solderable by depositing chemically afirst, temporary, layer of zinc from a solution of zinc oxide andcaustic soda, removing the first zinc layer with nitric acid solution,and depositing a second, permanent zinc layer on the now clean surfaceof the aluminum. The second zinc layer has an activated surface and anickel layer is formed on this surface by the action of a reducing agenton an acid solution of nickel chloride with sodium hypophosphite orsodium borohydride. The surface 33 of the passivating layer on thesemi-conductor device surrounding the solder protrusions 32 is renderednon-wettable by molten solder, so that molten solder does not spreadover this surface. The solder protrusions 32 are formed in a precisemanner and are accurately located on the surface 33.

The difference between the length of each side of each square-shapedaperture 30 in the masking member 25 and the length of each side of eachsquare-shaped device 21 is arranged to be at most equal to the radius ofthe hemispherical solder protrusions 32 on the device. Further, thearrangement is such that, when the semiconductor device 21 is insertedinto the aperture 30, and is correctly oriented in relation to thelongitudinal axis of the lead frame strip 10, each solder protrusioncontact 32, inevitably, is exclusively opposite to the conductor endportion 16 with which it is required to be connected. This lattercriterion is ensured by the accuracy of the size of the aperture 30 ofthe masking member 25 and by the closeness of the fit of the devicewithin the aperture 30; by the accuracy with which the conductor endpotions 16 and the device contacts are formed, respectively, on theinsulating substrate 12 and the device 21; and by the accuracy of thelocation of the aperture 30 of the masking member 25 in relation to theconductor end portions 16, when the lead frame strip 10 and the maskingmember 25 are in the desired registration with each other.

Thus, it is only necessary to ensure that the correspondingsemiconductor devices 21 are correctly orientated in relation to thelongitudinal axis of the lead frame strip when inserted in the aperture30 of the masking member 25. The device 21 may be inserted manually inthe apertures 30 or, as shown in FIG. 2, the apparatus 20 may includeautomatic means 35 for inserting the devices. The automatic means 35includes a suction head for holding the devices, and indexing mechanismfor raising and lowering the head, in the direction of the arrow 36, todeposit the devices in the aperture 30, and for moving the head betweena position over an aperture 30 and a position where it is capable ofpicking up a device. In any event, the devices 21 may be placed in theapertures 30 without employing precision optical aligning means, and ata faster rate than the locating of a semiconductor device over endconductor portions of a lead frame to a sufficient degree over endportions of a lead frame to a sufficient degree of accuracy by precisionoptical aligning means.

The carrier lead frame strip 10, whilst on the worktable 22, and afterthe semiconductor devices 21 have been inserted in the apertures 30 inthe masking member 25, is heated by means 38 to cause the solderprotrusions 32 on the device 21 to melt. When resolidified, and thedevices 21 are bonded to the carrier lead frames, the solder forms thedesired electrical interconnections between the semiconductor devices 21and the conductors 14 of the carrier lead frames 11. Whilst molten,surfaces tension forces cause the solder to have the least possiblesurface areas and, thus, each semiconductor device is pulled in theplane of the semiconductor device into exact registration with theconductor end portions 16 of the carrier lead frame 11, if the initialplacing of the semiconductor device 21 in the aperture 30 has notachieved this. The solder protrusions 32 melt at the temperature of183°C, and the performances of silicon semiconductor devices are notadversely affected by subjecting the semiconductor devices to thistemperature.

The semiconductor devices 21 are mounted on the carrier lead frames 11to provide so-called flip-chip structures.

Thus, the devices 21 are mounted on the strip 10, and are removed fromthe apertures 30 in the masking member 25 when the masking member 25 isseparated from the strip 10 at the second sprocket wheel 23. The strip10, with the semiconductor devices mounted thereon, is wound up on thereel 24.

In one particular embodiment according to the present invention theaccuracy of the size and the location of the sprocket holes 15 in thecarrier lead frame strip 10, the sprocket holes 26 in the masking member25, and the apertures 30 in the masking members 25, is ± 15 × 10⁻ ⁴inch.

Subsequently, each carrier lead frame 11, with the associatedsemiconductor devices 21, is severed from the strip 10. The part of thepolyimide substrate 13 beneath the carrier lead frame is removed withthe carrier lead frame. The exposed surfaces of the remaining outerportions of each conductor 14 are then soldered in co-operatingconductors 40 of a larger, main lead frame 41, as shown in FIG. 5, tocomplete the support for the device 21. The main lead frame 41 is madeof nickel plated with silver, and is stamped from a composite sheet in amulti-stage process. Each carrier lead frame 11 is secured to theco-operating main lead frame 41 by employing a conventional reflowsoldering process. The soldering action occurs at regions of the leadframes 11 and 41 remote from the semiconductor device and, thus, theseregions of the lead frames may be subjected to the solder meltingtemperature without adversely affecting the performance of thesemiconductor device.

The package for the semiconductor device 21 is completed byencapsulating the semiconductor device and the carrier lead frame in anepoxy resin 43 moulded in situ around the combination, as shown in FIG.6. The conductors 40 of the main lead frame 41 are then renderedelectrically discrete by removing the boundary part 44 of the main leadframe 41 by breaking tie-bars 45 extending between the conductors 40 ofthe main lead frame. The completed package 46 has the so-called"flat-pack" construction.

A plurality of main lead frames 41 also are initially in the form of astrip 47, and a plurality of semiconductor device-carrier lead framecombinations may be mounted simultaneously on the strip 47, and may beencapsulated in the epoxy resin 43, in a batch process. Suction meansfor positioning the combinations on the main lead frames 41, mouldingapparatus for the epoxy resin 43 and severing means to render theconductors 40 of the main lead frames electrically discrete, all may beembodied in apparatus to enable these process steps to be completedautomatically. The boundary part 44 of each main lead frame 41 of thestrip 47 is provided with sprocket holes 48 to ensure that the strip 47is correctly positioned at different stages in the automatic apparatusemployed in performing each of these steps.

Another embodiment of a lead frame strip 50 is shown in FIGS. 7 to 9,and parts of this lead frame strip identical with or closely resemblingparts of the carrier lead frame strip 10 of FIGS. 1 to 6 are given thesame reference numbers as the parts of FIGS. 1 to 6 the direction ofmovement of the carrier lead frame strip of FIGS. 7 to 9 through theapparatus is from left to right as viewed in the drawing and asrepresented by the arrow 56 shown in FIG. 8.

The conductors 51 of the lead frames 52 of the lead frame strip 50 arearranged to co-operate with contacts 32 on four sides of a semiconductordevice 53.

In FIG. 8, which corresponds to FIG. 3, and is a plan view of themasking member 54 whilst in the desired registration on the lead framestrip 50, the lead frames 52 beneath the masking member 54 are indicatedin broken line form, except for the conductor end portions 16 exposedthrough the apertures 55 in the masking member 54. The right-hand sideof this Figure shows the arrangement of the apertures 55 and the leadframes 52. The left hand side of the Figure shows semiconductor deviceswithin the apertures 55.

Each square-shaped aperture 55 in the masking member 54 has walls whichare inclined at 45° to the longitudinal axis 12 of the lead frame strip.When a semiconductor device 53 is inserted in an aperture 55, and is fedthrough the apparatus on the lead frame strip 50, inevitably it becomescontiguous with the following walls of the aperture so that its positionwithin the aperture 55 is known precisely. Means, such as a brush withglass fibre bristles, and shown in broken line form at 58 in FIG. 2, isemployed to ensure that each semiconductor device 53 is swept to becontiguous with the following walls of the aperture 55.

FIG. 9 corresponds to FIG. 4, comprising a section of the masking member54 on the lead frame strip 50, and shows a semiconductor device 53 readyto be mounted on a lead frame 52.

Instead of the whole of the lead frames being tinned, solder protrusions60, of the same size as the solder protrusions 32 on the semiconductordevices 53, are formed on the end portions 16 of the lead frameconductors 51. The arrangement of the masking member 54 when in thedesired registration with the lead frame spring 50 is such that, with acorresponding semiconductor device 53 inserted into an aperture 55, andcorrectly orientated in relation to the longitudinal axis 12 of the leadframe strip 50, each solder protrusion device contact 32 inevitably isexclusively opposite to the protrusion 60 on the conductor with which itis required to be connected. This criterion is ensured by the accuracywith which the conductor end portions, the protrusions 60 and the devicecontact protrusions 32 are formed; and by the accuracy of the locationof the aperture 55 of the masking member 54 in relation to the conductorend portions 16.

Thus, when the solder is melted, to form the desired electricalinterconnections between the device contacts and the conductors, theco-operating pairs of protrusions coalesce with each other, and surfacetension forces ensure that the device contacts are in exact registrationwith the end portions 16 of the conductors 51.

The lead frame strip 50 is not provided on an insulating substrate, butis stamped from a metal sheet in a precision way in a multi-stagestamping process. Thus, the lead frame strip 50 closely resembles themain lead frame strip 47 of FIG. 5. Further, each lead frame 52comprises the sole support for the semiconductor device 53.

For convenience a device 53 with only eight contacts 32 is illustrated,but it will be appreciated that the device may have many more contactsalong its periphery.

The lead frame strips 50 is wound around a reel after the semiconductordevices 53 have been mounted on the strip, and because the lead framestrip is not on an insulating substrate a separate insulating sheet isprovided between the turns of the lead frame strip when wound upon thereel.

Although each semiconductor device 53 is mounted only on a single leadframe 52, the extension of the outer portions of the conductor 14 of acarrier lead frame 11 beyond the periphery of the semiconductor device21 ensures that it is easier to mount such a combination on a main leadframe 41 of FIG. 5, than to mount the semiconductor device on the singlelead frame 52 of FIGS. 7 to 9 having dimensions corresponding to thoseof the main lead frame 41. This is because the inner end portions of theconductors 40 of the main lead frame 41 are spaced further apart thanfor a single lead frame 52. Thus, the locating of the carrier leadframe-semiconductor device combination over these inner end portions ofthe conductors 40 of the main lead frame 41 is easier than for thesemiconductor device 53 alone over the inner end portions of theconductors of the single lead frame 52.

The contacts of the semiconductor devices may be of any suitable form,and need not necessarily comprise protrusions of solder.

The apparatus 20, described above with reference to FIG. 2, may takemany different forms. In particular, the means for feeding the leadframe strip and the masking member in the desired registration with eachother through the apparatus may take any convenient form. Thus, it maynot include sprocket wheels, or it may include only one sprocket wheel,or it may have a different sprocket wheel or wheels to feed the carriedlead frame strip and the masking strip.

The masking member instead of having a plurality of apertures, may haveonly one aperture. Thus, the masking member may be placed repetitivelyin the desired registration on the lead frames on the worktable. Hence,after a semiconductor device has been inserted into the aperture and hasbeen bonded to a lead frame, the masking member is removed, the leadframe strip is displaced to bring a different lead frame onto theworktable, and the masking member is replaced in the desiredregistration with the new lead frame on the worktable. Such areciprocating action may also be employed with a masking member having aplurality of apertures, in each location of the masking member on thelead frame strip a plurality of lead frames being exposed partiallythrough the apertures in the masking member.

In any event, when a masking member with a plurality of apertures isprovided, a plurality of semiconductor devices may be mountedsimultaneously on the lead frame strip in a batch process, by multi-headautomatic apparatus.

The semiconductor devices may be tested after they are mounted on thelead frame strip and if found to be faulty, or to be improperly mounted,may be removed.

The conductors 14 of the carrier lead frames 11 of the strip 10initially may be formed electrically isolated from each other when thesilver layer is etched.

The lead frames 11, 52 and 41 may be of any convenient material, forexample, the carrier lead frame 11 may be of copper instead of silver.The insulating substrate 13, when provided, may be of a polyester of apolyamide instead of a polyimide.

The final encapsulation of the semiconductor device 21 or 53 may be inany suitable moulding compound, or may be within an evacuated enclosure,the parts of which enclosure are sealed hermetically in the conductors14, 51 or 40 of the lead frames.

Instead of a dual-in-line completed package as shown in FIG. 6 thepackage may have conductors extending from each side of a square orrectangular shaped package. In either such arrangement, the ends of theconductors beyond the encapsulation for the semiconductor device may bebent so that they may be received in a co-operating socket.

A carrier lead frame-semiconductor device combination may be mounted ona conventional header arrangement, instead of a main lead frame, inorder to complete the support for the device.

What is claimed is:
 1. Apparatus for mounting semiconductor devices eachof which are rectangular-shaped in plan and having contacts thereoncomprising a continuous strip including a plurality of lead frames, thelead frames being uniformly spaced along the longitudinal axis of thestrip, each lead frame having a matrix of conductors, the end portionsof which are adapted for connection to contacts of a correspondingsemiconductor device, a masking member defining at least onerectangular-shaped aperture for accurately locating a semiconductordevice, means for feeding the lead frame strip and masking memberlongitudinally between a first and a second station with the aperturedefined in the masking member being in a desired registration on a leadframe of the lead frame strip such that the conductor end portions ofthat lead frame are exposed through the aperture, means at one of saidstations for precisely positioning the lead frame and the masking memberwith respect to each other such that when a corresponding semiconductordevice is inserted in the required orientation into the aperture eachdevice contact is exclusively opposite to a co-operating conductor endportion, and bonding means disposed between said first and said secondstation and adjacent the paths of travel of said lead frame strip andmasking member for bonding the device contacts to the cooperatingconductor end portions.
 2. Apparatus as claimed in claim 1 in which theaperture defined in the masking member in square-shaped in plan, andfurther including means disposed between said first and said secondstation for positioning a corresponding semiconductor device which isalso square-shaped in plan in said aperture.
 3. Apparatus as claimed inclaim 1 in which the masking member defines a plurality of aperturesdisposed along the longitudinal axis of the masking member, and saidlead frame strip and masking member being fed adjacent each other suchthat consecutive apertures expose conductor end portions of consecutivelead frames of the lead frame strip.
 4. Apparatus as claimed in claim 1wherein said means for feeding includes at least one sprocket wheel atone of said station, said sprocket wheel engaging co-operating sprocketholes formed in both the masking member and the lead frame strip to feedthe masking member and the lead frame strip in the desired registrationwith each other between said first and said second stations uponrotation of said sprocket wheel.
 5. Apparatus as claimed in claim 1including means for automatically inserting corresponding semiconductordevices in each aperture defined in the masking member when the maskingmember is in the desired registration with the lead frame strip, saidinserting means being disposed adjacent the path of travel of themasking member and the lead frame strip and between the first and secondstations.
 6. Apparatus as claimed in claim 1 wherein said means forfeeding the lead frame strip and masking member including a first wheelrotatably supported at said first station, a second wheel rotatablysupported at said second station, at least one of said wheels being asprocket wheel, said lead frame strip and said masking member eachincluding sprocket holes spaced along the length thereof and saidsprocket wheel being disposed so as to engage the sprocket holes of saidlead frame strip and said masking member and feed said strip and saidmember in a controlled manner.
 7. Apparatus as set forth in claim 6wherein the sprocket holes of the masking member are different in sizeand spaced apart by a different amount than the sprocket holes of thelead frame strip to take into account the curvatuve of the sprocketwheel over which the lead frame strip and masking member pass, said leadframe strip and masking member being disposed to pass over said sprocketwheel together.
 8. Apparatus for mounting semiconductor devices eachrectangular-shaped in plan on a strip of corresponding lead frames, thelead frames being uniformly spaced along the longitudinal axis of thestrip, each lead frame having a matrix of conductors, the end portionsof which are adapted for connection to contacts of a correspondingsemiconductor device comprises a masking member defining at least onerectangular-shaped aperture, means for feeding the lead frame striplongitudinally between a first and a second station with the aperturedefined in the masking member being in a desired registration on a leadframe of the lead frame strip such that the conductor end portions forconnection to contacts of a corresponding semiconductor device areexposed through the aperture, said feeding means including means forprecisely positioning the lead frame and the aperture such that when acorresponding semiconductor device is inserted in the requiredorientation into the aperture each device contact is exclusivelyopposite to a co-operating conductor end portion, and means between saidfirst and said second stations for bonding the device contacts to theco-operating conductor end portions, the aperture defined in the maskingmember having dimensions to allow a corresponding semiconductor deviceto be a sufficiently close fit within the aperture to ensure that eachdevice contact exclusively is opposite to the conductor end portion towhich the contact is to be connected when the masking member is in therequired registration with the lead frame.
 9. Apparatus as claimed inclaim 8 wherein said means for feeding the lead frame strip and maskingmember including a first wheel rotatably supported at said firststation, a second wheel rotatably supported at said second station, atleast one of said wheels being a sprocket wheel, said lead frame stripand said masking member each including sprocket holes spaced along thelength thereof and said sprocket wheel being disposed so as to engagethe sprocket holes of said lead frame strip and said masking member andfeed said strip and said member in a controlled manner.
 10. Apparatus asclaimed in claim 8 in which the aperture defined in the masking memberin square-shaped in plan and disposed to receive a correspondningsemiconductor device which is also square-shaped in plan.
 11. Apparatusas claimed in claim 8 in which the masking member includes a pluralityof apertures, consecutive apertures exposing conductor end portions ofconsecutive lead frames of the lead frame strip.
 12. Apparatus asclaimed in claim 8 wherein said means for feeding includes at least onesprocket wheel, said sprocket wheel engaging co-operating sprocket holesformed in both the masking member and the lead frame strip to feed themasking member and the lead frame strip to the desired registration witheach other through said part of the apparatus upon rotation of saidsprocket wheel.
 13. Apparatus as claimed in claim 8 further includingautomatic inserting means for inserting corresponding semiconductordevices in each aperture defined in the masking member when the maskingmember is in the desired registration with the lead frame strip, saidinserting means being disposed adjacent the path of travel of themasking member and the lead frame strip and between the first and secondstations.
 14. Apparatus for mounting semiconductor devices eachrectangular-shaped in plan on a strip of corresponding lead frames, thelead frames being uniformly spaced along the longitudinal axis of thestrip, each lead frame having a matrix of conductors, the end portion ofwhich are adapted for connection to contacts of a correspondingsemiconductor device comprises a masking member defining at least onerectangular-shaped aperture, means for feeding the lead frame striplongitudinally between a first and a second station with the aperturedefined in the masking member being in a desired registration in a leadframe of the lead frame strip such that conductor end portions forconnection to contacts of a corresponding semiconductor device areexposed through the aperture, said feeding means including means forprecisely positioning the lead frame and the aperture such that when acorresponding semiconductor device is inserted to the requiredorientation into the aperture each device contact is exclusivelyopposite to a co-operating conductor end portion, and means between saidfirst and second stations for bonding the device contacts to thecooperating conductor end portions, the lead frame strip and the maskingmember being fed one atop the other the aperture defined in the maskingmember such that the leading walls of the aperture as the masking memberis fed between said stations are inclined in relation to thelongitudinal axis of the lead frame strip and each device contactexclusively is opposite to the conductor end portion to which thecontact is to be connected when the masking member is in the requiredregistration with the lead frame and the device is contiguous with thefollowing walls of the aperture.
 15. Apparatus as claimed in claim 14including means for maintaining the semiconductor device contiguous withthe following walls of the aperture.
 16. Apparatus as claimed in claim15 in which the means for maintaining the corresponding semiconductordevice contiguous with the following walls of the aperture comprises abrush with brush being mounted adjacent the path of travel of the leadframe strip and masking member to sweep the semiconductor device intothe required position as the masking member and the lead frame strip arefed from the first station to said second station.
 17. Apparatus asclaimed in claim 14 wherein said means for feeding the lead frame stripand masking member including a first wheel rotatably supported at saidfirst station, a second wheel rotatably supported at said secondstation, at least one of said wheels being a sprocket wheel, said leadframe strip and said masking member each including sprocket holes spacedalong the length thereof and said sprocket wheel being disposed so as toengage the sprocket holes of said lead frame strip and said maskingmember and feed said strip and said member in a controlled manner. 18.Apparatus as claimed in claim 14 in which the aperture defined in themasking member is square-shaped in plan and disposed to receive acorresponding semiconductor device which is also square-shaped in plan.19. Apparatus as claimed in claim 14 in which the masking memberincludes a plurality of apertures, that consecutive apertures exposingconductor end portions of consecutive lead frames of the lead framestrip.
 20. Apparatus as claimed in claim 14 wherein said means forfeeding includes at least one sprocket wheel, said sprocket wheelengaging co-operating sprocket holes formed in both the masking memberand the lead frame strip to feed the masking member and the lead framestrip to feed the masking member and the lead frame strip in the desiredregistration with each other through said part of the apparatus uponrotation of said sprocket wheel.
 21. Apparatus as claimed in claim 14further including automatic inserting means for inserting correspondingsemicondutor devices in each aperture defined in the masking member whenthe masking member is in the desired registration with the lead framestrip, said inserting means being disposed adjacent the path of travelof the masking member and the lead frame strip and between the first andsecond stations.
 22. Apparatus for mounting semiconductor devices eachrectangular-shaped in plan on a strip of corresponding lead frames, thelead frames being uniformly spaced along the longitudinal axis of thestrip, each lead frame having a matrix of conductors, the end portionsof which are adapted for connection to contacts of a correspondingsemiconductor device, comprises a masking member defining at least onerectangular-shaped aperture for accurately locating the semiconductordevices, means for feeding the lead frame strip and the masking memberlongitudinally between a first and a second station with the aperturedefined in the masking member being in a desired registration on a leadframe of the lead frame strip such that conductor end portions forconnection to contacts of a corresponding semiconductor device areexposed through the aperture, the lead frame strip and the maskingmember being fed one atop the other such that the lead frame and theaperture are in the required orientation for insertion into the apertureof a semiconductor device with each device contact being exclusivelyopposite to a co-operating conductor end portion, means disposed betweensaid stations for bonding the device contacts to the co-operatingconductor end portions, and said means for feeding said lead frame stripand masking member includes at least one sprocket wheel at one of saidstations, said sprocket wheel engaging co-operating sprocket holesformed in both the masking member and the lead frame strip to feed themasking member and the lead frame strip in the desired registration witheach other continuously between said first and said second stations uponrotation of said sprocket wheel.
 23. Apparatus as claimed in claim 22wherein the sprocket holes of the masking member are spaced apart by adifferent amount than the sprocket holes of the lead frame strip tocompensate for the curvature of the sprocket wheels.
 24. Apparatus asclaimed in claim 23 wherein said cooperating sprocket holes of saidmasking member and said lead frame strip are of different size tocompensate for the curvature of the sprocket wheels.
 25. Apparatus asclaimed in claim 24 in which the aperture defined in the masking memberis dimensioned to allow a corresponding semiconductor device to be asufficiently close fit within the aperture so as to ensure that eachdevice contact exclusively is opposite to the conductor end portion towhich the contact is to be connected when the masking member is in therequired registration with the lead frame.
 26. Apparatus as claimed inclaim 24 in which the leading walls of the aperture as the maskingmember is fed through the apparatus are inclined in relation to thelongitudinal axis of the lead frame strip, and each device contactexclusively is opposite to the conductor end portion to which thecontact is to be connected when the masking member is in the requiredregistration with the lead frame and the device is contiguous with thefollowing walls of the aperture.
 27. Apparatus as claimed in claim 26further including means for positioning the corresponding semiconductordevice contiguous with the following walls of the aperture when themasking member is in the desired registration with the lead frame strip.28. Apparatus as claimed in claim 27 in which the means for positioningthe corresponding semiconductor device contiguous with the followingwalls of the aperture comprises a brush mounted between said stationsand adjacent the path of travel of the masking member and lead framestrip to sweep the semiconductor device into the required position asthe masking member and the lead frame strip are fed between saidstations.
 29. Apparatus as claimed in claim 24 in which the aperturedefined in the masking member is a square-shaped in plan and is arrangedto receive a corresponding semiconductor device which is alsosquare-shaped in plan.
 30. Apparatus as claimed in claim 24 in which themasking member includes a plurality of apertures, consecutive aperturesexposing conductor end portions of consecutive lead frames of the leadframe strip.